A building on the 1300 block of 13th Street NW partially collapsed Wednesday afternoon and a construction worker was seriously hurt, D.C. fire said.

The second floor of a three-story row house under renovation fell while the unit was unoccupied, spokesman Vito Maggiolo said.

D.C. fire responded to the call at 1:59 p.m. Photos from the department’s Twitter account show large piles of construction materials, wood and pink insulation at the site.

The worker’s injury was not life-threatening, Maggiolo said. An investigation into the cause of the collapse is ongoing.